How would you model a pyramid pattern?
You can model the pyramids either scaling extruded individual faces to 0 and then removing doubles(w->r), or you could poke the faces(alt+p) and then select the middle vertices by the amount of adjacent faces or connecting edges(shift+g menu) and use Shrink/Flatten(alt+s) to move them outwards in the direction the surface is facing. You could then grow selection(ctrl++) and bevel(ctrl+b) the edges so they remain sharp(ish) after Subdivision Surface modifier. You could crease the edges(shift+e) instead of beveling to have them completely sharp with the Subsurf, but that would be a bit unrealistic since edges are rarely completely sharp.